June 2026 Was a Top-5 Hottest June on Record for Boston, Philly and DC — But Not Texas

June 2026 was a top-5 hottest June on record for Boston, Miami, Philadelphia and Washington DC, and it ran more than 3°F above normal from Seattle to Portland. But it was not a nationwide scorcher. Across the 27 major cities we pulled from our NOAA records database, the heat split the country in two: the East Coast and the West baked, while Texas and the Midwest finished near or below their long-term average. San Antonio ended June 1.6°F below normal; Memphis, 1.7°F below.

Boston posted the biggest anomaly of any city we checked — 4.6°F above its 1970–2025 June average, its 4th-warmest June in 57 years. And the month didn't so much end as detonate: a heat dome that built in the final days of June carried straight into the Fourth of July weekend, breaking century-old records up and down the Eastern Seaboard.

The forecasts called it — our own Summer 2026 outlook flagged above-normal heat for most of the country. What the monthly numbers add is the geography. This wasn't a coast-to-coast oven. Of the 27 cities I analyzed, 6 landed a top-7 hottest June in more than half a century of records — and all of them sit along the Eastern Seaboard or in the Pacific Northwest: Boston, Philadelphia, Seattle, Portland, Washington, Miami. Meanwhile the south-central US, which usually owns the summer heat headlines, spent June under a cooler, stormier pattern.

To measure it cleanly, I pulled every daily high from each city's primary long-record weather station — mostly 57 unbroken years of June data — and compared June 2026 to that station's own 1970–2025 June average. That “anomaly” number matters more than the raw temperature: 74°F in Seattle is a bigger heat story than 91°F in Dallas, because Seattle almost never does 74°F in June and Dallas always does 91°F.

The clearest signal in the data is a stripe of red running from Boston to Washington. Every major East Coast metro finished the month above normal, and four of them — Boston (+4.6°F, 4th-warmest), Philadelphia (+3.8°F, 5th), Washington DC (+3.0°F, 5th) and Baltimore (+2.1°F, 10th) — ranked among the ten hottest Junes those stations have ever logged.

It came in two waves. The first hit mid-month: DC touched 100°F on June 12, and Philadelphia climbed to 98°F the same week. Then the pattern briefly relaxed before the real event — a sprawling heat dome that built over the final days of the month and refused to break. By early July, that dome had pushed DC to 102°F, Philadelphia to 103°F and Boston to 101°F, with more than 20 cities breaking daily records in a single day. Washington's new mark surpassed a record that had stood since 1872, and the capital's Fourth of July was forecast as its hottest on record.

For a region where summer highs sit in the low 80s, this was genuinely unusual — not the kind of number Phoenix would blink at, but 3 to 5 degrees above a 56-year baseline is a lot of heat to sustain for 30 straight days. It also lands squarely in the trend we documented in our analysis of the cities where summer has warmed the most since 1990.

The hottest raw numbers, of course, belong to the desert. Phoenix averaged a 106.8°F daily high for the month and cleared 90°F on all 30 days — topping out at 111°F on June 16. Las Vegas ran 102.3°F (peak 109°F) and El Paso 99.0°F (peak 107°F). None of those is a record for the Southwest — Phoenix ranked its 11th-hottest June, Vegas its 13th — but all three ran roughly 2°F above their already-brutal norms.

That's the thing about the desert heat story: the extremes are so high that a 2°F anomaly barely registers in the headlines, yet it pushes an already-dangerous month further into the red. If you want the long view on how these cities stack up, we ranked them in our hottest states and cities in America analysis, and covered this summer's early desert extremes in the Southwest heat wave 2026 piece.

The anomaly that should raise eyebrows isn't Phoenix — it's Seattle. The city averaged a 73.7°F June high, 3.5°F above normal and its 7th-warmest June on record, and touched 91°F on June 15 — a temperature Seattle sees only a handful of days in an entire summer. Portland ran a nearly identical +3.3°F, hitting 96°F. The Northwest doesn't have the air-conditioning penetration of the Sun Belt, which is exactly why a June like this one gets dangerous fast — the same vulnerability that turned the 2021 heat dome deadly.

Here's the part most national coverage missed: a big chunk of the country had a perfectly ordinary, even cool, June. Chicago finished 1.0°F below its average (36th-warmest of 57 Junes). Memphis was 1.7°F below, its 42nd-warmest. Houston, Kansas City and San Antonio all landed below normal too — San Antonio a full 1.6°F under, despite a 96°F peak.

The reason is the same one that cooked the coasts. A ridge locked over the East and another over the West, but between them a trough kept the south-central states cooler, cloudier and wetter than usual — the classic signature of a developing El Niño. For a state-by-state look at how that plays out, see our El Niño effects by state breakdown.

The way June ended matters more than the way it started. The heat dome that broke records over the July 4th weekend is the same pattern that dominated the month — and the CDC has flagged “extremely high” rates of heat-related ER visits across the affected region. When roughly 180 million Americans are under a heat alert to open July, the odds favor more of the same East-and-West-hot, middle-milder split through the heart of summer.

Curious how your own town did? You can pull the daily high for any US city on any date — including every day of this June — with our weather-on-this-day lookup on the homepage. And for the all-time context behind these numbers, see every state's hottest June on record and the hottest temperatures ever recorded.